Display device

ABSTRACT

A display device includes a display panel, a light source, and a reflective sheet. The reflective sheet includes a four-sided bottom face part with two pairs of mutually opposing sides, a first peripheral portion extending from one of the sides, and a second peripheral portion with a first section extending from adjacent one of the sides and a second section extending from the first section. The first peripheral portion and the second section of the second peripheral portion partially overlap with each other at a location between ends of the one of the sides to form one of side face parts of the reflective sheet. The second peripheral portion forms adjacent one of the side face parts of the reflective sheet that is adjacent to the one of the side face parts of the reflective sheet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2013-170744 filed on Aug. 20, 2013. The entire disclosure of JapanesePatent Application No. 2013-170744 is hereby incorporated herein byreference.

BACKGROUND

1. Field of the Invention

The present invention generally relates to a display device. Morespecifically, the present invention relates to a display device equippedwith a reflective sheet for reflecting light from a light source towarda display panel.

2. Background Information

Display devices are known that are equipped with a reflective sheet forreflecting light from a light source toward a display panel (seeJapanese Patent No. 4,903,253 (Patent Literature 1), for example).

Patent Literature 1 discloses a display device equipped with a concavereflective sheet for reflecting the light from the light source towardthe display panel.

SUMMARY

The present invention is directed to various features of a displaydevice with a reflective sheet.

One object is to provide a display device having a reflective sheet withwhich a concave shape of the reflective sheet can be easily maintained,without the use of any reinforcing member, even though the reflectivesheet is made thinner. Another object is to provide a display devicewith which the image is less likely to shake as a result of vibration orimpact.

In view of the state of the known technology, a display device includesa display panel, a light source, and a reflective sheet. The lightsource is configured to emit light from a rear side relative to thedisplay panel toward the display panel. The reflective sheet is disposedon the rear side relative to the display panel, and is configured toreflect the light from the light source toward the display panel. Thereflective sheet includes a four-sided bottom face part with two pairsof mutually opposing sides, a first peripheral portion extending fromone of the sides of the bottom face part, and a second peripheralportion with a first section extending from adjacent one of the sides ofthe bottom face part that is adjacent to the one of the sides and asecond section extending from the first section. The first peripheralportion and the second section of the second peripheral portionpartially overlap with each other at a location between ends of the oneof the sides of the bottom face part to form one of side face parts ofthe reflective sheet while the reflective sheet is installed to thedisplay device. The second peripheral portion forms adjacent one of theside face parts of the reflective sheet that is adjacent to the one ofthe side face parts of the reflective sheet while the reflective sheetis installed to the display device.

Also other objects, features, aspects and advantages of the presentdisclosure will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses one embodiment of the display device.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a perspective view of a display device in accordance with afirst embodiment;

FIG. 2 is an exploded perspective view of the display device illustratedin FIG. 1;

FIG. 3 is a developed view of a reflective sheet used in the displaydevice in accordance with the first embodiment;

FIG. 4A is a detail view of a corner part of the reflective sheetillustrated in FIG. 3;

FIG. 4B is a detail view in which the corner part illustrated in FIG. 4Ais further enlarged;

FIG. 5 is an elevational view of the reflective sheet illustrated inFIG. 3 in its assembled state;

FIG. 6 is a developed view of a reflective sheet used in a displaydevice in accordance with a second embodiment;

FIG. 7A is a detail view of a corner part of the reflective sheetillustrated in FIG. 6;

FIG. 7B is a detail view in which the corner part illustrated in FIG. 7Ais further enlarged;

FIG. 8 is an elevational view of the reflective sheet illustrated inFIG. 6 in its assembled state;

FIG. 9 is a developed view of a reflective sheet used in a displaydevice in accordance with a third embodiment;

FIG. 10 is an elevational view of the reflective sheet illustrated inFIG. 9 in its assembled state;

FIG. 11 is a perspective view of a reflective sheet in accordance with acomparative example;

FIG. 12 is an elevational view of the reflective sheet illustrated inFIG. 11;

FIG. 13 is a side view of the reflective sheet illustrated in FIG. 11,illustrating the function of the reflective sheet;

FIG. 14 is a developed view of a reflective sheet in accordance with acomparative example;

FIG. 15 is a diagram illustrating a state when a side face part of areflective sheet in accordance with a comparative example are sagged;

FIG. 16 illustrates a cantilevered beam formula under the condition inwhich the side face part is considered to be a single board;

FIG. 17 is a perspective view of a reflective sheet in accordance with acomparative example in which folded parts are provided to adjacent sideface parts, respectively;

FIG. 18A is an elevational view of a reflective sheet in accordance witha comparative example in its assembled state;

FIG. 18B is a developed view of the reflective sheet illustrated in FIG.18A;

FIG. 19A is an elevational view of a reflective sheet in accordance witha comparative example in its assembled state, the reflective sheethaving a greater height of a bottom face part; and

FIG. 19B is a developed view of the reflective sheet illustrated in FIG.19A.

DETAILED DESCRIPTION OF EMBODIMENTS

Selected embodiments will now be described through reference to thedrawings. It will be apparent to those skilled in the art from thisdisclosure that the following descriptions of the embodiments areprovided for illustration only and not for the purpose of limiting theinvention as defined by the appended claims and their equivalents. Theconstituent elements, the layout positions and connection modes of theconstituent elements, and so forth given in the following embodimentsare just provided for illustration only and not for the purpose oflimiting the invention. The invention is merely defined by the appendedclaims. Of the constituent elements in the following embodiments, thosenot discussed in an independent claim are not necessarily required, butwill be described for understanding of the embodiments.

First Embodiment

Configuration of Display Device

FIG. 1 is a perspective view of a display device A in accordance with afirst embodiment. FIG. 2 is an exploded perspective view of the displaydevice A. In FIG. 2, the direction on the forward side is labeled the Z1direction, and the direction on the rearward side is labeled the Z2direction.

The display device A includes a front cabinet 3, a plurality of bezels4, a display panel 5, a molded frame 6, an optical sheet 7, a reflectivesheet 1, and a rear frame 2. The front cabinet 3 is a frame-shapedmember disposed on the forward side of the display device A. The bezels4 protect the outer frame of the display panel 5 and are provided alongthe outer frame. The display panel 5 is a liquid crystal panel, forexample, and displays images.

The molded frame 6 is a member that supports the display panel 5 fromits rear face side. The optical sheet 7 has a plurality of members, suchas a diffuser and a light guide sheet.

The rear frame 2 is a member that serves as the rear housing of thedisplay device A. A recess 2A having a bottom face 2A1 whose sizecorresponds to a bottom face part 11 of the reflective sheet 1 is formedin the rear frame 2.

The bottom face part 11 of the reflective sheet 1 is disposed on thebottom face 2A1 of the recess 2A via a heat sink or an LED substrate(not shown). Thus, the rear frame 2 functions as a rear face sidesupport member that supports the bottom face part 11 of the reflectivesheet 1 from the rear face side.

The rear frame 2 has an outer peripheral part 2A2. Flaps 17 of thereflective sheet 1 overlap the outer peripheral part 2A2.

The reflective sheet 1 is a member that reflects light from LEDs 200(light emitting diodes; light sources) toward the display panel 5. Theflaps 17 that overlap the outer peripheral part 2A2 of the rear frame 2are formed on the outer peripheral part of the reflective sheet 1. Inthe illustrated embodiment, the display device A is illustrated as aliquid crystal display device with LEDs. However, the present inventionis not limited to this type of display device, and can be applied to adisplay device having different types of display panels, or havingdifferent types of light sources.

Configuration of Reflective Sheet

FIG. 3 is a developed view of the reflective sheet 1 used in the displaydevice A in accordance with the first embodiment. FIG. 4A is a detailview of a corner part of the reflective sheet 1. FIG. 4B is a detailview in which the corner part in FIG. 4A is further enlarged. FIG. 5 isan elevational view of the reflective sheet 1 in its assembled state.

In FIGS. 3 to 5, the right direction is labeled the X1 direction, theleft direction is labeled the X2 direction, the upward direction islabeled the Y1 direction, and the downward direction is labeled the Y2direction. The corner part shown in FIGS. 4A and 4B is the upper-leftcorner 19 in FIG. 3. The other corners 19 (the upper-right, lower-left,and lower-right corners 19) have the same configuration as the cornerpart shown in FIGS. 4A and 4B, and therefore are not depicted ordescribed.

With this reflective sheet 1, a plurality of through-holes 11A throughwhich the LEDs 200 are passed are formed in the bottom face part 11. Thereflective sheet 1 has four of the corners 19. A cut-out 18 is formed ineach of these four corners 19.

The cut-outs 18 are formed in the reflective sheet 1 as shown in FIG.4A. By forming these cut-outs 18 an apex P1 is formed while a protrudingtab 170A and an end portion 170B contact with each other when thereflective sheet 1 is assembled. As shown in FIG. 4A, at each corners19, a second perforation 14B (indicated by a one-dot chain line in FIG.4A) is formed extending from the apex P1 toward the outside with respectto the upward and downward directions (diagonally downward to the leftin FIG. 4A). These second perforations 14B form display panel-side edges21 when the reflective sheet 1 is assembled into a concave shape.

The protruding tabs 170A, which are parallel to the second perforations14B, are provided near the second perforations 14B. The protruding tabs170A each have an end portion 170A1 on the apex P1 side, and an endportion 170A2 on the opposite side from the apex P1. Edges 270 areprovided on extensions of the second perforations 14B from the endportions 170A2, respectively.

As shown in FIG. 4B, for example, at each corners 19, the edge 270 formsa region 2700 in the form of a right triangle, indicated by hatchinggoing diagonally downward to the right, in the overlapping portion 23(discussed below). This region 2700 has three apexes 270A, 270B, and270C. The apex 270C is a point that serves as the starting point of anedge 29 that is parallel in the upward and downward directions. Asdiscussed below, at each corners 19, a first slit 15 is formed using theapex 270C as its starting point P2.

As shown in FIGS. 4A and 4B, at each corners 19, a second perforation14A (indicated by one-dot chain lines in FIGS. 4A and 4B) is formed at aposition that is a width D away from the edge 29. This width D matcheshow far the protruding tabs 170A protrude from the second perforations14B. These second perforations 14A are formed parallel to the edges 29,and form the display panel-side edges 21 when the reflective sheet 1 isfolded into a concave shape.

As shown in FIG. 4A, with the reflective sheet 1, a pair of secondperforations 14C (indicated by a one-dot chain line in FIG. 4A) are alsoformed, which extend in the horizontal direction between the apexes P1.These second perforations 14C are formed parallel to edges 30, separatedby the width D from the edges 30 in the vertical direction. The secondperforations 14C form display panel-side edges 22 when the reflectivesheet 1 is assembled into a concave shape.

When the second perforations 14A and 14B are mountain folded, they formthe display panel-side edges 21, and when the second perforations 14Care mountain folded, they form the display panel-side edges 22. When thesecond perforations 14A, 14B, and 14C are mountain folded, the regionsbetween them and the end portions of the reflective sheet 1 form theflaps 17.

First perforations 13 (indicated by broken lines) are also formed in thereflective sheet 1. As shown in FIG. 5, when the first perforations 13are valley folded, this forms one bottom face part 11, a pair of shortedge-side side face parts 12(1) that include the short edges 11B of thebottom face part 11, and a pair of long edge-side side face parts 12(2)that include the long edges 11C of the bottom face part 11.

The first perforations 13 on the short edge-side side face parts 12(1)side form the short edges 11B of the bottom face part 11 when thereflective sheet 1 is assembled into a concave shape. The firstperforations 13 on the long edge-side side face parts 12(2) side formthe long edges 11C of the bottom face part 11 when the reflective sheet1 is assembled into a concave shape.

Holes 130 are formed in the four corners of the bottom face part 11 sothat overlapping portions 24 of first regions 12A (discussed below) willeasily go from second slits 16 (discussed below) into the rear of thebottom face part 11 (the side away from the viewer in the drawing).

As shown in FIG. 5, the display panel-side edges 21 each have two apexesP1, P1. As shown in FIG. 4A, at each corners 19, the first slit 15 isformed in the display panel-side edge 21. The starting point of thefirst slit 15 is a position (in this example, the starting point P2)within a predetermined proximity range of a reference apex (thisreference apex is the apex P1), and the first slit 15 extends toward theshort edge 11B of the bottom face part 11 and has its end point P3 atthe short edge 11B.

As shown in FIG. 3, the first slits 15 divide the short edge-side sideface parts 12(1) into a first region 12A that includes the referenceapex P1 and a second region 12B that does not include the reference apexP1.

As shown in FIG. 4A, at each corners 19, the second slit 16 is formedextending from the end point P3 of the first slit 15, along the shortedge 11B of the bottom face part 11, toward the long edge-side side facepart 12(2) on the side closer to the first slit 15 out of the pair oflong edge-side side face parts 12(2), with the end point P4 being thehole 130 in the bottom face part 11.

As shown in FIG. 4A, at each corners 19, the first region 12A formed bythe first slit 15 has a first overlapping portion 23 that includes thefirst slit 15 (a predetermined region on the first slit 15 side), and asecond overlapping portion 24 that includes the second slit 16 (the endportion of the first region 12A on the second slit 16 side). In FIG. 4A,the first overlapping portion 23 is indicated by hatching goingdiagonally downward to the right, and the second overlapping portion 24is indicated by hatching going diagonally downward to the left.

With the reflective sheet 1 with this configuration, in the course ofassembly work, as discussed above, the first perforations 13 are valleyfolded, and the second perforations 14A to 14C are mountain folded. Atthis point, the holes 130 make it easier for the second overlappingportions 24 of the first regions 12A to go through the second slits 16and into the rear side of the bottom face part 11 (the side away fromthe viewer). Thus, the worker puts the second overlapping portions 24into the rear side of the bottom face part 11 (the side away from theviewer).

After this, the worker brings the first regions 12A formed by the firstslits 15 into contact with the surface of the second regions 12B (theside toward the viewer).

Operation

As a result, the first overlapping portions 23 (see FIG. 4A), which arepredetermined ranges of the first regions 12A on the first slit 15 sideof the first regions 12A, overlap predetermined ranges or regions 25 ofthe second region 12B on the first slit 15 side of the second regions12B (the region indicated by two-dot chain line hatching; see FIG. 4A).Consequently, as shown in FIG. 5, overlapping parts 20 are formed wherethe overlapping portions 23 overlap the regions 25.

Also, the second overlapping portions 24 (see FIG. 4A), which arepredetermined ranges of the first regions 12A on the second slit 16 sideof the first regions 12A, overlap predetermined regions 26 of the bottomface part 11 (the region indicated by two-dot chain line hatching; seeFIG. 4A). Consequently, as shown in FIG. 5, overlapping parts 31 areformed where the overlapping portions 24 overlap the regions 26. Thushaving the overlapping portions 24 overlap the regions 26 results in theoverlapping portions 24 of the first regions 12A being supported by thesecond slits 16.

Furthermore, as shown in FIG. 4A, because the overlapping portions 23 ofthe first regions 12A overlap the regions 25 of the second regions 12B,the protruding tabs 170A and the end portions 170C of the second regions12B overlap each other. This forms overlapping portions 28 in which theflaps 17 overlap each other.

Effect

With the above configuration, the overlapping portions 24 of the firstregions 12A overlap with the regions 26 of the bottom face part 11.Thus, the first regions 12A are less likely to waver. Therefore, theoverlapping portions 23 of the first regions 12A can overlap the regions25 of the second regions 12B more securely. Consequently, the stiffnessof the short edge-side side face parts 12(1) becomes higher.

As a result, a reflective sheet can be provided with which the concaveshape of the reflective sheet can be more easily maintained, without theuse of any reinforcing member even though the reflective sheet is madethinner, and the image is less likely to shake as a result of vibrationor impact, without increasing the developed surface area.

Also, the second slits 16 are formed starting at the starting point P3of the first slits 15, along the short edges 11B of the bottom face part11, and toward the long edge-side side face parts 12(2) on the side ofthe first slits 15 closer to the end point P3. Thus, the second slits 16can be shorter in length.

Therefore, as discussed above, unlike when the second slits 111 areformed in the entire vertical direction of the bottom face part 11,there will be less increase in the developed surface area. Thus, thestiffness of the short edge-side side face parts 12(1) can be increased.

Furthermore, as discussed above, the overlapping portions 28 are formedwhere the flaps 17 overlap each other. Consequently, there is anincrease in the thickness of part of the flaps 17. Thus, the shape ofthe flaps 17 can be stabilized.

Position of Reference Apex within Proximity Range

The position of the apex (reference apex) P1 within the proximity rangeis preferably a position that does not reach the center portion alongthe display panel-side edges 21 from the apex P1, and more precisely, isnear the end portions 170A2 of the protruding tabs 170A, out of theedges 270 formed by the extension of the protruding tabs 170A (see FIGS.4A and 4B).

In other words, the position can be such that there is no loss of theconcave shape of the reflective sheet 1 even though the overlappingportions 23 and 24 overlap the regions 25 and 26 within a range from theapex P1 to a position that does not reach the center part of the shortedge-side side face parts 12(1).

Other

In the illustrated embodiment, only the upper-left corner 19A isdescribed above. However, the overlapping parts 20 and 31 and theoverlapping portions 28 of the flaps 17 are also formed by the methoddiscussed above for the lower-left corner 19B, the upper-right corner19C, and the lower-right corner 19D.

Thus, the operation and effect obtained with the lower-left corner 19B,the upper-right corner 19C, and the lower-right corner 19D are the sameas those obtained with the above-mentioned upper-left corner 19A.

In particular, as shown in FIG. 5, since two of the overlapping parts 20are formed at the short edge-side side face parts 12(1), the stiffnessof the short edge-side side face parts 12(1) will be higher than whenthere is only one overlapping part 20.

In the illustrated embodiment, the display device A includes the displaypanel 5, the LED 200 (e.g., the light source), and the reflective sheet1. The LED 200 (e.g., the light source) is configured to emit light froma rear side relative to the display panel 5 toward the display panel 5.The reflective sheet 1 is disposed on the rear side relative to thedisplay panel 5, and is configured to reflect the light from the LED 200(e.g., the light source) toward the display panel 5. The reflectivesheet 1 includes the four-sided bottom face part 11 with two pairs ofmutually opposing edges 11B, 11C (e.g., sides), the second region 12B(e.g., the first peripheral portion) extending from the short edge 11B(e.g., one of the sides) of the bottom face part 11, and the secondperipheral portion (12A, 12(2)) with the side face part 12(2) (e.g., thefirst section) extending from the long edge 11C (e.g., the adjacent oneof the sides) of the bottom face part 11 that is adjacent to the shortedge 11B (e.g., the one of the sides) and the first region 12A (e.g.,the second section) extending from the side face part 12(2). The secondregion 12B and the first region 12A of the second peripheral portion(12A, 12(2)) partially overlap with each other at a location betweenends of the short edge 11B of the bottom face part 11 to form the sideface part 12(1) (e.g., one of side face parts) of the reflective sheet 1while the reflective sheet 1 is installed to the display device A. Theside face part 12(2) of the second peripheral portion (12A, 12(2)) formsthe side face part 12(2) (e.g., adjacent one of the side face parts) ofthe reflective sheet 1 that is adjacent to the side face part 12(1) ofthe reflective sheet 1 while the reflective sheet 1 is installed to thedisplay device A.

With the display device A, the first region 12A is folded relative tothe side face part 12(2) to form the corner 19 (e.g., the cornerportion) of the reflective sheet 1 between the side face part 12(1) ofthe reflective sheet 1 and the side face part 12(2) of the reflectivesheet 1 while the reflective sheet 1 is installed to the display deviceA.

With the display device A, the second region 12B and the first region12A are disposed adjacent to each other via the first slit 15 thatextends in a direction intersecting with the short edge 11B of thebottom face part 11 and has one end on the short edge 11B of the bottomface part 11.

With the display device A, the reflective sheet 1 further includes thethird peripheral portion (12A, 12(2)) with the side face part 12(2)(e.g., the first section) extending from the long edge 11C (e.g.,opposing one of the sides) of the bottom face part 11 that is oppositethe long edge 11B (e.g., the adjacent one of the sides) of the bottomface part 11 and the first region 12A (e.g., the second section)extending from the side face part 12(2). The second region 12B (e.g.,the first peripheral portion) and the first region 12A (e.g., the secondsection of the third peripheral portion) partially overlap with eachother at a location between the ends of the short edge 11B (e.g., theone of the sides) of the bottom face part 11 to form the side face part12(1) (e.g., the one of the side face parts) of the reflective sheet 1while the reflective sheet 1 is installed to the display device A.

With the display device A, the second region 12B (e.g., the firstperipheral portion) and the first region 12A (e.g., the second sectionof the third peripheral portion) are disposed adjacent to each other viathe first slit 15 (e.g., the additional first slit) that extends in adirection intersecting with the short edge 11B (e.g., the one of thesides) of the bottom face part 11 and has one end on the short edge 11B(e.g., the one of the sides) of the bottom face part 11.

With the display device A, the bottom face part 11 and the first region12A are disposed adjacent to each other via the second slit 16 thatextends along the short edge 11B of the bottom face part 11. The secondslit 16 extends from the one end of the first slit 15 to the long edge11C (e.g., the adjacent one of the sides) of the bottom face part 11.

The display device A further includes the rear frame 2 (e.g., thesupport member) supporting the bottom face part 11 of the reflectivesheet 1 from the rear side.

With the display device A, the second region 12B and the first region12A have flaps 17 that extend from the display panel-side edges 21(e.g., the outer edge portions) of the second region 12B and the firstregion 12A, respectively. The flaps 17 of the second region 12B and thefirst region 12A are disposed on the outer peripheral part 2A2 of therear frame 2 such that the flaps 17 partially overlap with each otherwhile the reflective sheet 1 is installed to the display device A.

With the display device A, the bottom face part 11 has a rectangularshape. The short edge 11B (e.g., the one of the sides) of the bottomface part 11 is shorter than the long edge 11C (e.g., the adjacent oneof the sides) of the bottom face part 11.

Second Embodiment

Referring now to FIGS. 6, 7A, 7B and 8, a display device A with areflective sheet 1A in accordance with a second embodiment will now beexplained. In view of the similarity between the first and secondembodiments, the parts of the second embodiment that are identical tothe parts of the first embodiment will be given the same referencenumerals as the parts of the first embodiment. Moreover, thedescriptions of the parts of the second embodiment that are identical tothe parts of the first embodiment may be omitted for the sake ofbrevity.

Configuration of Reflective Sheet

FIG. 6 is a developed view of the reflective sheet 1A used in thedisplay device A (see FIG. 1) in accordance with a second embodiment.FIG. 7A is a detail view of a corner part of the reflective sheet 1Aillustrated in FIG. 6. FIG. 7B is a detail view in which the corner partin FIG. 7A is further enlarged. FIG. 8 is an elevational view of thereflective sheet 1A in FIG. 6 in its assembled state.

In FIGS. 6 to 8, the right direction is labeled the X1 direction, theleft direction is labeled the X2 direction, the upward direction islabeled the Y1 direction, and the downward direction is labeled the Y2direction. The corner shown in FIGS. 7A and 7B is the upper-left corner19 in FIG. 6. The other corners 19 (the upper-right, lower-left, andlower-right corners 19) are the same as the corner 19 shown in FIGS. 7Aand 7B, and therefore are not depicted or described.

As shown in FIG. 7A, at each corners 19, a second perforation 14D(indicated by a one-dot chain line in FIG. 7A) is formed extending fromthe apex P1 toward the outside with respect to the horizontal direction(diagonally upward to the right in FIG. 7A). These second perforations14D form display panel-side edges 22 when the reflective sheet 1A isassembled into a concave shape.

Protruding tabs 170E, which are parallel to the second perforations 14D,are provided near the second perforations 14D. The protruding tabs 170Eeach have an end portion 170E1 on the apex P1 side, and an end portion170E2 on the opposite side from the apex P1. Edges 300 are provided onextensions of the second perforations 14D from the end portions 170E2,respectively.

As shown in FIG. 7B, for example, at each corners 19, the edge 300 formsa region 3000 in the form of a right triangle, indicated by hatchinggoing diagonally downward to the right, in the overlapping portions 35(discussed below). This region 3000 has three apexes 300A, 300B, and300C. The apex 300C is a point that serves as the starting point of anedge 30 that is parallel to the left and right direction. As discussedbelow, at each corners 19, a first slit 15 is formed using the apex 300Cas its starting point P2.

As shown in FIGS. 7A and 7B, at each corners 19, a second perforation14C is formed at a position that is a width D away from the edge 30. Thewidth D matches how far the protruding tabs 170E protrude from thesecond perforations 14D. These second perforations 14C are formedparallel to the edges 30, and form the display panel-side edges 22 whenthe reflective sheet 1A is folded into a concave shape.

As shown in FIG. 7A, with the reflective sheet 1A, a pair of secondperforations 14A (indicated by a one-dot chain line in FIG. 7A) are alsoformed, which extend in the vertical direction between the apexes P1.These second perforations 14A are formed parallel to edges 29, separatedby the width D from the edges 29 in the left and right direction. Thesecond perforations 14A form the display panel-side edges 21 when thereflective sheet 1A is assembled into a concave shape.

When the second perforations 14C and 14D are mountain folded, they formthe display panel-side edges 22, and when the second perforations 14Aare mountain folded, they form the display panel-side edges 21. When thesecond perforations 14A, 14C, and 14D are mountain folded, the regionsbetween them and the end portions of the reflective sheet 1A form theflaps 17.

First perforations 13 (indicated by broken lines) are also formed in thereflective sheet 1A. As shown in FIG. 8, when the first perforations 13are valley folded, this forms one bottom face part 11, a pair of shortedge-side side face parts 12(1) that include the short edges 11B of thebottom face part 11, and a pair of long edge-side side face parts 12(2)that include the long edges 11C of the bottom face part 11.

The first perforations 13 on the short edge-side side face parts 12(1)side form the short edges 11B of the bottom face part 11 when thereflective sheet 1 is assembled into a concave shape. The firstperforations 13 on the long edge-side side face parts 12(2) side formthe long edges 11C of the bottom face part 11 when the reflective sheet1 is assembled into a concave shape.

Holes 130 are formed in the four corners of the bottom face part 11 sothat overlapping portions 35 of first regions 12C (discussed below) willeasily go from second slits 16 (discussed below) into the rear of thebottom face part 11 (the side away from the viewer in the drawing).

As shown in FIG. 8, the display panel-side edges 21 each have two apexesP1, P1. As shown in FIG. 7A, at each corners 19, the first slit 15 isformed in the display panel-side edge 22. As shown in FIG. 7A, thestarting point of the first slit 15 is a position (in this example, thestarting point P2) within a predetermined proximity range of a referenceapex (this reference apex is the apex P1), and the first slit 15 extendstoward the long edge 11C of the bottom face part 11 and has its endpoint P3 at the long edge 11C.

As shown in FIG. 6, the first slits 15 divide the long edge-side sideface parts 12(2) into a first region 12C that includes the referenceapex P1 and a second region 12D that does not include the reference apexP1.

As shown in FIG. 7A, at each corners 19, the second slit 16 is formedextending from the end point P3 of the first slit 15, along the longedges 11C of the bottom face part 11, toward the short edge-side sideface part 12(1) on the side closer to the first slit 15 out of the pairof short edge-side side face parts 12(1), with the end point P4 beingthe hole 130 in the bottom face part 11.

As shown in FIG. 7A, at each corners 19, the first regions 12C formed bythe first slit 15 has a first overlapping portion 35 that includes thefirst slit 15 (a predetermined region on the first slit 15 side), and asecond overlapping portion 36 that includes the second slit 16 (the endportion of the first region 12A on the second slit 16 side). In FIG. 7A,the first overlapping portion 35 is indicated by hatching goingdiagonally downward to the right, and the second overlapping portion 36is indicated by hatching going diagonally downward to the left.

With the reflective sheet 1 with this configuration, in the course ofassembly work, as discussed above, the first perforations 13 are valleyfolded, and the second perforations 14A, 14C, and 14D are mountainfolded. At this point, the holes 130 make it easier for the secondoverlapping portions 36 of the first regions 12C to go through thesecond slits 16 and into the rear side of the bottom face part 11 (theside away from the viewer). Thus, the worker puts the second overlappingportions 36 into the rear side of the bottom face part 11 (the side awayfrom the viewer).

After this, the worker brings the first regions 12C formed by the firstslits 15 into contact with the surface of the second regions 12D (theside toward the viewer).

Operation

As a result, the first overlapping portions 35 (see FIG. 7A), which arepredetermined ranges of the first regions 12C on the first slit 15 sideof the first regions 12C, overlap predetermined ranges or regions 37 ofthe second regions 12D on the first slit 15 side of the second regions12D (the region indicated by two-dot chain line hatching; see FIG. 7A).Consequently, as shown in FIG. 8, overlapping parts 20 are formed wherethe overlapping portions 35 overlap the regions 37.

Also, the second overlapping portions 36 (see FIG. 7A), which arepredetermined ranges of the first regions 12C on the second slit 16 sideof the first regions 12C, overlap predetermined regions 38 of the bottomface part 11 (the region indicated by two-dot chain line hatching; seeFIG. 7A). Consequently, as shown in FIG. 8, overlapping parts 31 areformed where the overlapping portions 36 overlap the regions 38. Thushaving the overlapping portions 36 overlap the regions 38 results in theoverlapping portions 35 of the first regions 12C being supported by thesecond slits 16.

Furthermore, as shown in FIG. 7A, because the overlapping portions 35 ofthe first regions 12C overlap the regions 37 of the second regions 12C,the protruding tabs 170E and the end portions 170C of the second regions12D overlap each other. This forms overlapping portions 28 in which theflaps 17 overlap each other.

Effect

With the above configuration, the overlapping portions 36 of the firstregions 12C overlap with the regions 38 of the bottom face part 11.Thus, the first regions 12C are less likely to waver. Therefore, theoverlapping portions 35 of the first regions 12C can overlap the regions37 of the second regions 12D more securely. Consequently, the stiffnessof the long edge-side side face parts 12(2) becomes higher.

As a result, a reflective sheet can be provided with which the concaveshape of the reflective sheet can be more easily maintained, without theuse of any reinforcing member even though the reflective sheet is madethinner, and the image is less likely to shake as a result of vibrationor impact, without increasing the developed surface area.

Also, the second slits 16 are formed starting at the starting point P3of the first slits 15, along the long edges 11C of the bottom face part11, and toward the short edge-side side face parts 12(1) on the side ofthe first slits 15 closer to the end point P3. Thus, the second slits 16can be shorter in length.

Therefore, unlike when the second slits 111 are formed in the entirehorizontal direction of the bottom face part 11, there will be lessincrease in the developed surface area. Thus, the stiffness of the longedge-side side face parts 12(2) can be increased.

Furthermore, as discussed above, the overlapping portions 28 are formedwhere the flaps 17 overlap each other. Consequently, there is anincrease in the thickness of part of the flaps 17. Thus, the shape ofthe flaps 17 can be stabilized.

Position of Reference Apex within Proximity Range

The position of the apex (reference apex) P1 within the proximity rangeis preferably a position that does not reach the center portion alongthe display panel-side edges 22 from the apex P1, and more precisely, isnear the end portions 170E2 of the protruding tabs 170E, out of theedges 300 formed by the extension of the protruding tabs 170E (see FIGS.7A and 7B).

In other words, the position can be such that there is no loss of theconcave shape of the reflective sheet 1A even though the overlappingportions 35 and 36 overlap the regions 37 and 38 within a range from theapex P1 to a position that does not reach the center part of the longedge-side side face parts 12(2).

Other

In the illustrated embodiment, only the upper-left corner 19A isdescribed above. However, the overlapping parts 20 and 31 andoverlapping portions 28 of the flaps 17 are also formed by the methoddiscussed above for the lower-left corner 19B, the upper-right corner19C, and the lower-right corner 19D.

Thus, the operation and effect obtained with the lower-left corner 19B,the upper-right corner 19C, and the lower-right corner 19D are the sameas those obtained with the above-mentioned upper-left corner 19A.

In particular, since two of the overlapping parts 20 are formed at thelong edge-side side face parts 12(2), the stiffness will be higher atthe long edge-side side face parts 12(2), which tend to sag when thethickness is reduced.

In the illustrated embodiment, the display device A includes the displaypanel 5, the LED 200 (e.g., the light source), and the reflective sheet1. The LED 200 (e.g., the light source) is configured to emit light froma rear side relative to the display panel 5 toward the display panel 5.The reflective sheet 1A is disposed on the rear side relative to thedisplay panel 5, and is configured to reflect the light from the LED 200(e.g., the light source) toward the display panel 5. The reflectivesheet 1A includes the four-sided bottom face part 11 with two pairs ofmutually opposing edges 11B, 11C (e.g., sides), the second region 12D(e.g., the first peripheral portion) extending from the long edge 11C(e.g., one of the sides) of the bottom face part 11, and the secondperipheral portion (12C, 12(1)) with the side face part 12(1) (e.g., thefirst section) extending from the short edge 11B (e.g., the adjacent oneof the sides) of the bottom face part 11 that is adjacent to the longedge 11C (e.g., the one of the sides) and the first region 12C (e.g.,the second section) extending from the side face part 12(1). The secondregion 12D and the first region 12C of the second peripheral portion(12C, 12(1)) partially overlap with each other at a location betweenends of the long edge 11C of the bottom face part 11 to form the sideface part 12(2) (e.g., one of side face parts) of the reflective sheet1A while the reflective sheet 1A is installed to the display device A.The side face part 12(1) of the second peripheral portion (12C, 12(1))forms the side face part 12(1) (e.g., adjacent one of the side faceparts) of the reflective sheet 1A that is adjacent to the side face part12(2) of the reflective sheet 1A while the reflective sheet 1A isinstalled to the display device A.

With the display device A, the first region 12C is folded relative tothe side face part 12(1) to form the corner 19 (e.g., the cornerportion) of the reflective sheet 1A between the side face part 12(2) ofthe reflective sheet 1A and the side face part 12(1) of the reflectivesheet 1A while the reflective sheet 1A is installed to the displaydevice A.

With the display device A, the second region 12D and the first region12C are disposed adjacent to each other via the first slit 15 thatextends in a direction intersecting with the long edge 11C of the bottomface part 11 and has one end on the long edge 11C of the bottom facepart 11.

With the display device A, the reflective sheet 1A further includes thethird peripheral portion (12C, 12(1)) with the side face part 12(1)(e.g., the first section) extending from the short edge 11B (e.g.,opposing one of the sides) of the bottom face part 11 that is oppositethe short edge 11B (e.g., the adjacent one of the sides) of the bottomface part 11 and the first region 12C (e.g., the second section)extending from the side face part 12(1). The second region 12D (e.g.,the first peripheral portion) and the first region 12C (e.g., the secondsection of the third peripheral portion) partially overlap with eachother at a location between the ends of the long edge 11C (e.g., the oneof the sides) of the bottom face part 11 to form the side face part12(2) (e.g., the one of the side face parts) of the reflective sheet 1Awhile the reflective sheet 1A is installed to the display device A.

With the display device A, the second region 12D (e.g., the firstperipheral portion) and the first region 12C (e.g., the second sectionof the third peripheral portion) are disposed adjacent to each other viathe first slit 15 (e.g., the additional first slit) that extends in adirection intersecting with the long edge 11C (e.g., the one of thesides) of the bottom face part 11 and has one end on the long edge 11C(e.g., the one of the sides) of the bottom face part 11.

With the display device A, the bottom face part 11 and the first region12C are disposed adjacent to each other via the second slit 16 thatextends along the long edge 11C of the bottom face part 11. The secondslit 16 extends from the one end of the first slit 15 to the short edge11B (e.g., the adjacent one of the sides) of the bottom face part 11.

The display device A further includes the rear frame 2 (e.g., thesupport member) supporting the bottom face part 11 of the reflectivesheet 1A from the rear side.

With the display device A, the second region 12D and the first region12C have flaps 17 that extend from the display panel-side edges 22(e.g., the outer edge portions) of the second region 12D and the firstregion 12C, respectively. The flaps 17 of the second region 12D and thefirst region 12C are disposed on the outer peripheral part 2A2 of therear frame 2 such that the flaps 17 partially overlap with each otherwhile the reflective sheet 1A is installed to the display device A.

With the display device A, the bottom face part 11 has a rectangularshape. The long edge 11C (e.g., the one of the sides) of the bottom facepart 11 is longer than the the short edge 11B (e.g., the adjacent one ofthe sides) of the bottom face part 11.

Third Embodiment

Referring now to FIGS. 9 and 10, a display device A with a reflectivesheet 1B in accordance with a third embodiment will now be explained. Inview of the similarity between the first and third embodiments, theparts of the third embodiment that are identical to the parts of thefirst embodiment will be given the same reference numerals as the partsof the first embodiment. Moreover, the descriptions of the parts of thethird embodiment that are identical to the parts of the first embodimentmay be omitted for the sake of brevity.

Configuration of Reflective Sheet

FIG. 9 is a developed view of the reflective sheet 1B used in thedisplay device A in accordance with a third embodiment. FIG. 10 is anelevational view of the reflective sheet 1B illustrated in FIG. 9 in itsassembled state.

The third embodiment is a combination of the first and secondembodiments. Therefore, those constituent elements that are the same asin the reflective sheets 1 and 1A discussed above will be numbered thesame and will not be described again.

With this reflective sheet 1B, a pair of first slits 15 and a pair ofsecond slits 16 are formed in the upper-left corner 19A and thelower-right corner 19D. The starting points of the first slits 15 arethe positions P2 on the long edge-side side face parts 12(2), just aswith the reflective sheet 1A discussed above. The second slits 16 areformed from the end points of the first slits 15 toward the shortedge-side side face parts 12(1) on the side closer to the first slits15, respectively.

Meanwhile, another pair of first slits 15 and another pair of secondslits 16 are are formed in the lower-left corner 19B and the upper-rightcorner 19C. The starting points of the first slits 15 are the positionsP2 on the short edge-side side face parts 12(1), just as with thereflective sheet 1 discussed above. The second slits 16 are formed fromthe end points of the first slits 15 toward the long edge-side side faceparts 12(2) on the side closer to the first slits 15, respectively.

Effect

With this configuration, a single overlapping part 20 is formed in eachof the pair of short edge-side side face parts 12(1) and the pair oflong edge-side side face parts 12(2). Thus, the stiffness of all of theside face parts 12(1) and 12(2) can be increased. Also, overlappingportions 28 are formed at all of the flaps 17, namely, the flaps 17 onthe side of the pair of short edge-side side face parts 12(1) and theflaps 17 on the side of the pair of long edge-side side face parts12(2). Thus, the thickness is increased in part of each of the fourflaps 17. Therefore, the overall stiffness of the four flaps 17 can beincreased.

In the illustrated embodiment, the display device A includes the displaypanel 5, the LED 200 (e.g., the light source), and the reflective sheet1B. The LED 200 (e.g., the light source) is configured to emit lightfrom a rear side relative to the display panel 5 toward the displaypanel 5. The reflective sheet 1B is disposed on the rear side relativeto the display panel 5, and is configured to reflect the light from theLED 200 (e.g., the light source) toward the display panel 5.

The reflective sheet 1B includes the four-sided bottom face part 11 withtwo pairs of mutually opposing edges 11B, 11C (e.g., sides), the secondregion 12F (e.g., the first peripheral portion) extending from the shortedge 11B (e.g., one of the sides) of the bottom face part 11, and thesecond peripheral portion with the second region 12H (e.g., the firstsection) extending from the long edge 11C (e.g., the adjacent one of thesides) of the bottom face part 11 that is adjacent to the short edge 11B(e.g., the one of the sides) and the first region 12E (e.g., the secondsection) extending from the second region 12H. The second region 12F andthe first region 12E partially overlap with each other at a locationbetween ends of the short edge 11B of the bottom face part 11 to formthe side face part 12(1) (e.g., one of side face parts) of thereflective sheet 1B while the reflective sheet 1B is installed to thedisplay device A. The second region 12H forms the side face part 12(2)(e.g., adjacent one of the side face parts) of the reflective sheet 1Bthat is adjacent to the side face part 12(1) of the reflective sheet 1Bwhile the reflective sheet 1B is installed to the display device A.

In the illustrated embodiment, with the display device A, the reflectivesheet 1B further includes the fourth peripheral portion (12F, 12G) withthe second region 12F (e.g., the first section) extending from the shortedge 11B (e.g., the other opposing one of the sides) of the bottom facepart 11 that is opposite the short edge 11B (e.g., the one of the sides)of the bottom face part 11 and the first region 12G (e.g., the secondsection) extending from the second region 12F. The second region 12H andthe first region 12G partially overlap with each other at a locationbetween ends of long edge 11C of the bottom face part 11 to form theside face part 12(2) (e.g., the adjacent one of the side face parts) ofthe reflective sheet 1B while the reflective sheet 1B is installed tothe display device.

In other words, the reflective sheet 1B includes the second region 12H(e.g., the first peripheral portion) extending from the long edge 11C(e.g., one of the sides) of the bottom face part 11, and the secondperipheral portion with the second region 12F (e.g., the first section)extending from the short edge 11B (e.g., the adjacent one of the sides)of the bottom face part 11 that is adjacent to the long edge 11C (e.g.,the one of the sides) and the first region 12G (e.g., the secondsection) extending from the second region 12F. The second region 12H andthe first region 12G partially overlap with each other at a locationbetween ends of the long edge 11C of the bottom face part 11 to form theside face part 12(2) (e.g., one of side face parts) of the reflectivesheet 1B while the reflective sheet 1B is installed to the displaydevice A. The second region 12H forms the side face part 12(1) (e.g.,adjacent one of the side face parts) of the reflective sheet 1B that isadjacent to the side face part 12(2) of the reflective sheet 1B whilethe reflective sheet 1B is installed to the display device A.

Also, with the display device A, the reflective sheet 1B furtherincludes the fourth peripheral portion (12H, 12E) with the second region12H (e.g., the first section) extending from the long edge 11C (e.g.,the other opposing one of the sides) of the bottom face part 11 that isopposite the long edge 11C (e.g., the one of the sides) of the bottomface part 11 and the first region 12E (e.g., the second section)extending from the second region 12H. The second region 12F and thefirst region 12E partially overlap with each other at a location betweenends of short edge 11B of the bottom face part 11 to form the side facepart 12(1) (e.g., the adjacent one of the side face parts) of thereflective sheet 1B while the reflective sheet 1B is installed to thedisplay device.

The present invention can be applied to a device that reflects a lightflux produced by LEDs and directs it toward a display panel, such as aliquid crystal display device.

COMPARATIVE EXAMPLES

Advantages of the reflective sheets 1 and 1A in accordance with thefirst to third embodiments will be explained in view of comparativeexamples.

FIG. 11 is a perspective view of a reflective sheet 100 in accordancewith a comparative example. FIG. 12 is an elevational view of thereflective sheet 100 illustrated in FIG. 11. In FIGS. 11 and 12, the Xaxis is the horizontal direction, and the Y axis is the verticaldirection.

This type of reflective sheet 100 includes a rectangular bottom facepart 101 and four side face parts 102 that are disposed so as tosurround the four sides of the bottom face part 101.

LED groups 200A to 200C, in which a plurality of LEDs 200 are arrangedin the horizontal direction, are disposed in a specific number of rows(three rows in this example) in the vertical direction on the bottomface part 101.

In FIGS. 11 and 12, overlaps 104A and 104B are formed at the boundaryportions of the two side face parts 102, respectively, so that the slits104 will not open up and lower the reflection efficiency of thereflective sheet 100. The overlaps 104A and 104B overlap the endportions of the adjacent side face parts 102, respectively.

FIG. 13 is a side view of the reflective sheet 100 illustrated in FIG.11, illustrating the function of the reflective sheet 100.

The reflective sheet 100 is attached above a rear frame 500. The sideface parts 102 of the reflective sheet 100 are disposed along thesurface of the rear frame 500.

Holes through which LEDs 200 are passed are formed in the bottom facepart 101 of the reflective sheet 100, and the LEDs 200 are passedthrough these holes. A diffuser 400 is provided in the optical axisdirection of the LEDs 200. The diffuser 400 diffuses light from the LEDs200.

The reflective sheet 100 reflects light other than the light thatreaches the diffuser 400 directly (such as the light axis L1). In otherwords, the reflective sheet 100 reflects light that does not reach thediffuser 400 directly and is not directly transmitted by the diffuser400 (such as the light axis L2), and allows this light to be transmittedby the diffuser 400. That is, the reflective sheet 100 “recycles” thelight by reflecting light not transmitted directly from the LEDs 200 tothe diffuser 400, and allowing this light to reach the diffuser 400.

FIG. 14 is a developed view of a reflective sheet 100 in accordance withanother comparative example. This reflective sheet 100 is produced bythe valley folding along perforations 103 that do not transmit light(the perforations 103 are indicated by broken lines). This forms arectangular bottom face part 101 and four side face parts 102, whicheach include one of the four sides of the bottom face part 101.

Slits 104 are formed in the four corners of the reflective sheet 100 sothat the valley folding along the perforations 103 will produce aconcave shape.

When the slits 104 are thus provided to the four corners, there tend tobe gaps where the slits 104 come together. Thus, with the display panelprovided above the reflective sheet 100, the light flux may not alwaysreach the positions directly over the slits 104. If this happens, theimage displayed on the display panel will tend to be uneven.

On the other hand, with the reflective sheet 100 illustrated in FIGS. 11and 12, the overlaps 104A and 104B are formed to help prevent this. Whenthe overlaps 104A and 104B contact with the adjacent side face parts102, respectively, it is less likely that gaps will be formed in thefour corners. However, overlapping the overlaps 104A and 104B with theadjacent side face parts 102 is not a simple job. This in turn increasesthe number of assembly steps.

There is also a method in which the mating parts of the slits 104 (seeFIG. 14) are reinforced with hooks, but the hooks can come loose if theystick out from the diffuser 400. Also, hooking the hooks together takesmore time.

It has been discovered that there is a need to reduce the thickness ofthe reflective sheet 100 in order to bring down costs. However, if thereflective sheet 100 is made thinner, then the stiffness of the sideface parts 102 is reduced, and the side face parts 102 tend to sag.

FIG. 15 is a diagram illustrating a state when the side face parts 102sag. The reflective sheet 100 can be fixed to a rear frame 2 (see FIG.2) by overlapping flaps 600 (provided to the side face parts 102) withouter peripheral parts 2A2 of the rear frame 2 (see FIG. 2).

Meanwhile, a plurality of holes 101A through which the LEDs 200 arepassed are formed in the bottom face part 101, and the bottom face part101 is placed on an LED substrate 700 on which the LEDs 200 are mounted.In this reflective sheet 100, the outer peripheral parts 2A2 of the rearframe 2 contribute to the fixing of the reflective sheet 100, but theLED substrate 700 does not contribute to the fixing of the reflectivesheet 100.

Thus, the side face part 102 can be considered as a single board that isfixed at just one end to a wall. This affords a “cantilever formula” inwhich the side face parts 102 are considered as a single board.

FIG. 16 is a diagram illustrating the “cantilevered beam formula” underthe condition in which the side face parts 102 are considered as asingle board. In FIG. 16, it is assumed that one end of the side facepart 102 considered to be a board or beam is fixed to a wall 900, andthe other end of the side face part 102 is not fixed.

In this case, E represents the vertical elastic coefficient of the sideface part 102, h represents the thickness of the side face part 102, Lrepresents the length of the side face part 102, b represents the widthof the side face part 102, and P represents the load exerted on theother end of the side face part 102. In this case, the moment of inertiaof area of the side face part 102 is expressed as 1_(z)=bh³/12.

The amount of sag v of the side face part 102 is v=PL³/3EL_(z). Thus,the lower is the thickness h of the side face parts 102, the lower isthe moment of inertia of area and the greater is the amount of sag v ofthe side face parts 102.

As discussed above, when the reflective sheet 100 is made thinner, theside face parts 102 tend to sag. This makes it difficult to maintain theconcave shape of the reflective sheet 100 in accordance with thecomparative example. In this case, a gap is more likely to occur betweentwo adjacent side face parts 102, resulting in image unevenness. Also,the side face parts 102 are apt to undulate as a result of vibration orimpact. This makes the image look as if it is shaking.

In view of this, with a reflective sheet in accordance with anothercomparative example illustrated in FIG. 17, in order to maintain theconcave shape of the reflective sheet even if this sagging occurs,folded parts 106 are provided to adjacent side face parts 102 such thatthe folded part formed on one side face part 102 is folded toward theadjacent side face part 102.

FIG. 17 illustrates the reflective sheet in which the folded parts 106are provided to the adjacent side face parts 102, respectively.

At the boundary between the adjacent side face parts 102(1) and 102(2),a concave part 105 is formed in one side face part 102(1) that mateswith the folded part 106(2) formed on the other side face part 102(2).

Also, the folded parts 106(1) are formed on the side face part 102(1),and are folded toward the other side face part 102(2).

Meanwhile, the folded part 106(2) is formed on the other side face part102(2), and is folded toward the side face part 102(1) and mates withthe concave part 105 formed in the side face part 102(1).

The folded parts 106(3) and a concave part (not shown) are also formedat the boundary between the side face part 102(1) and the side face part102(3) that is adjacent on the opposite side from the side face part102(2), just as at the boundary between the side face part 102(1) andthe side face part 102(2).

However, folding these folded parts 106(1) to 106(3) entails extra work,and leads to more assembly steps.

On the other hand, it has been discovered that with a reflective sheet100A illustrated in FIG. 18A in accordance with yet another comparativeexample, image unevenness, or image shake caused by vibration or impact,can be less likely to occur, and a concave shape can be easilymaintained without using any reinforcing members even when the thicknessof the reflective sheet is reduced.

FIG. 18A is an elevational view of the reflective sheet 100A in itsassembled state, and FIG. 18B is a developed view of the reflectivesheet 100A illustrated in FIG. 18A. In FIGS. 18A and 18B, the X axis isthe horizontal direction, and the Y axis is the vertical direction.

This reflective sheet 100A is assembled in a concave shape by valleyfolding along perforations 103 shown in FIG. 18B (indicated by brokenlines). Consequently, the reflective sheet 100A has a rectangular bottomface part 101 and four side face parts 102 that surround the bottom facepart 101. The bottom face part 101 has a pair of short sides 101(1) anda pair of long sides 101(2). As discussed below, second slits 111 areformed in the entire short sides 101(1).

Flaps 600 (see FIG. 15) are formed by mountain folding along theperforations 109 shown in FIG. 18B (indicated by one-dot chain lines).

On the reflective sheet 100A, first slits 110 that divide each of theside face parts 102 into two regions 102A and 102B are formed in thecenter portions of the pair of side face parts 102 on the side of thebottom face part 101 with the short sides 101(1) so as to reach theshort sides 101(1) of the bottom face part 101 in the horizontaldirection.

The second slits 111 are formed along the entire of the short sides101(1) of the bottom face part 101 so that the end portions 102C of theregions 102A on the side closer to the bottom face part 101 out of theregions 102A formed by the first slits 110, and the end portions 102D ofthe regions 102B on the side closer to the bottom face part 101 out ofthe regions 102B formed by the first slits 110 contact with the rearface (the side farthest from the viewer in the drawings) of the bottomface part 101.

With this configuration, when the perforations 103 indicated by thebroken lines are valley folded, the end portions 107 of the regions 102Aon the first slit 110 side and the end portions 108 of the regions 102Bon the first slit 110 side will overlap. At this point, the worker putsthe end portions 102C on the side of the regions 102A closer to thebottom face part 101, and the end portions 102D on the side of theregions 102B closer to the bottom face part 101 into the second slits111.

As shown in FIGS. 18A, this forms overlapping parts 20 between theregions 102A and the regions 102B. These overlapping parts 20 are fixedwhen the end portions 102C of the regions 102A and the end portions 102Dof the regions 102B overlap on the rear side of the bottom face part101.

With this reflective sheet 100A, the first slits 110 that reach all theway to the bottom face part 101 are formed in the center portions of thepair of side face parts 102, and the second slits 111 are formed in theentire short sides 101(1) of the bottom face part 101 perpendicular tothe first slits 110. However, the effect of the reflective sheet 100Adiscussed above is limited while the dimension (the length of the shortsides 101(1)) of the bottom face part 101 is short.

Therefore, the following problems are still encountered when the bottomface part 101 is large in the vertical direction.

FIG. 19A shows the assembled state of a reflective sheet 100B inaccordance with further another comparative example that has a greaterheight of the bottom face part 101, and FIG. 19B is a developed view ofthe reflective sheet 100B illustrated in FIG. 19A. In FIGS. 19A and 19B,the X axis is the horizontal direction, and the Y axis is the verticaldirection.

With this reflective sheet 100B, as shown in FIGS. 19A and 19B, thebottom face part 101 has a pair of short sides 101(1) that are longerthan the short sides 101(1) of the reflective sheet 100A discussedabove. The bottom face part 101 also has a pair of long sides 101(2).

With this reflective sheet 100B, the second slits 111 are formed in theentire short sides 101(1) of the bottom face part 101. Since the shortsides 101(1) of the bottom face part 101 are themselves longer thanthose of the reflective sheet 100A discussed above, the second slits 111are longer. Also, the second slits 111 have to be formed in anapproximately triangular shape in order to stabilize the concave shapewhen the reflective sheet 100B is assembled.

When the second slits 111 are thus made longer, the fixing of theregions 102A and 102B by the second slits 111 tends to be weak, andoverlapping between the regions 102A and the regions 102B tends to belost. As a result, the stiffness of the side face parts 102 of thereflective sheet 100B becomes lower.

Also, when the second slits 111 are made longer as shown in FIGS. 19Aand 19B, the second slits 111 have to be formed in an approximatelytriangular shape in order to stabilize the concave shape of thereflective sheet 100B. In this case, the developed surface area of thereflective sheet 100B becomes larger. And when the developed surfacearea is larger, the stiffness of the reflective sheet 100B alsodecreases.

On the other hand, with the reflective sheets 1 and 1A in accordancewith the first to third embodiments, unevenness of the brightness on thedisplay panel 5, or image shake caused by vibration or impact, will beless likely to occur, the concave shape of the reflective sheets 1 and1A can be maintained without using any reinforcing members even when thethickness is reduced, and the developed surface area can also bereduced.

The display device in accordance with one aspect of the presentinvention includes a display panel, a light source that is configured toemit light from the rear face side of the display panel toward thedisplay panel, and a reflective sheet that is disposed on the rear faceside of the display panel and reflects the light from the light sourcetoward the display panel. The reflective sheet is folded so as toinclude a four-sided bottom face part having two pairs of mutuallyopposing sides, and four side face parts disposed so as to surround thefour sides of the bottom face part, without any slits being formed atthe boundaries of the four side face parts. The four side face partseach have a display panel-side edge that is the edge on the displaypanel side, at least one first slit, whose starting point is a positionwithin a predetermined proximity range relative to a reference apex thatis one or both of two apexes on the display panel-side edge, out of thedisplay panel-side edges, and that extends toward the bottom face partand has an end point on the edge of the bottom face part, is formed ineach of at least one pair of mutually opposing side face parts. Thefirst slits divide the pair of side face parts into two regions each.Each of the two regions has a predetermined range on the first slitside, and the predetermined ranges of the two regions overlap eachother.

With this configuration, at least one first slit, whose starting pointis a position within the predetermined proximity range from thereference apex, out of the display panel-side edge that is the edge onthe display panel side, and whose end point is the edge of the bottomface part, is formed in each of at least one pair of side face parts outof the four side face parts. Each one of the pair of side face parts isdivided by the first slit into two regions, and predetermined ranges ofthe two regions on the first slit side overlap each other.

Therefore, overlapping portions, in which the two regions areoverlapping, are formed in each of at least one pair of side face parts.Thus, the overlap increases part of the thickness in at least one pairof side face parts. This increases the stiffness of at least one pair ofside face parts.

As a result, even if the reflective sheet is made thinner, it will beeasier to maintain the concave shape of the reflective sheet withoutusing any reinforcing members, and less likely that image unevennesswill occur, or shaking of the image caused by vibration or impact.

Also, two of the first slits, whose reference apexes are two apexes onthe display panel-side edge, can be formed in each of the pair of sideface parts.

With this configuration, since two first slits are formed in each of thepair of side face parts, there are overlapped portions at two places ona single side face part. As a result, compared to when there is only oneoverlapped portion, there are more places where the thickness isgreater. Thus, the stiffness of the side face parts can be increased.

Also, the configuration can be such that a second slit is formed whosestarting point is the end point of the first slit, and which extendsalong the edge of the bottom face part in the direction of the side facepart closest to the end point of the first slit. The two regions are afirst region in which the second slit is formed and a second region inwhich the second slit is not formed. The second slit supports the end ofthe reflective sheet on the second slit side.

With this configuration, since the second slit supports the end of thefirst region on the second slit side, the first and second regions canbe kept in a stable overlapping state.

Also, the configuration can further includes a rear face side supportmember that supports the bottom face part of the reflective sheet fromthe rear face side of the reflective sheet. Flaps that overlap the outerperipheral part of the rear face side support member are provided to thedisplay panel-side edge. When the two regions are overlapped, the flapsof the two regions overlap each other.

With this configuration, since the flaps of the regions overlap eachother when the two regions are overlapped, the thickness is greater at aportion of the flap, which increases the stiffness of the flaps.

Also, the configuration can be such that the bottom face part isrectangular, having two long sides that are parallel to each other, andtwo short sides that are parallel to each other, and the side face partsin which the first slits are formed are short-edge side face parts thatinclude the short sides.

With this configuration, since overlapping portions produced by thefirst slits are formed in the short-edge side face parts, the stiffnessof the short-edge side face parts can be increased.

Alternatively, the configuration can be such that the bottom face partis rectangular, having two long sides that are parallel to each other,and two short sides that are parallel to each other, and the side faceparts in which the first slits are formed are the pair of long-edge sideface parts that include the long sides.

With this configuration, since overlapping portions produced by thefirst slits are formed in the long-edge side face parts, the stiffnessof the long-edge side face parts can be increased.

Also, the configuration can be such that the first slits are formed inthe four side face parts, and one first slit is formed in the side faceparts.

With this configuration, since one overlapped portion produced by thefirst slit is formed in each of the four side face parts, the stiffnesscan be increased in all of the side face parts.

With the present invention, image unevenness, or image shake caused byvibration or impact, will be less likely to occur, and a concave shapecan be easily maintained without using any reinforcing members even whenthe thickness is reduced, all of which is accomplished withoutincreasing the developed surface area.

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts unless otherwise stated.

As used herein, the following directional terms “forward”, “rearward”,“front”, “rear”, “up”, “down”, “above”, “below”, “upward”, “downward”,“top”, “bottom”, “side”, “vertical”, “horizontal”, “perpendicular” and“transverse” as well as any other similar directional terms refer tothose directions of a display device in an upright position.Accordingly, these directional terms, as utilized to describe thedisplay device should be interpreted relative to a display device in anupright position on a horizontal surface. The terms “left” and “right”are used to indicate the “right” when referencing from the right side asviewed from the front of the display device, and the “left” whenreferencing from the left side as viewed from the front of the displaydevice.

Also it will be understood that although the terms “first” and “second”may be used herein to describe various components these componentsshould not be limited by these terms. These terms are only used todistinguish one component from another. Thus, for example, a firstcomponent discussed above could be termed a second component andvice-a-versa without departing from the teachings of the presentinvention. The term “attached” or “attaching”, as used herein,encompasses configurations in which an element is directly secured toanother element by affixing the element directly to the other element;configurations in which the element is indirectly secured to the otherelement by affixing the element to the intermediate member(s) which inturn are affixed to the other element; and configurations in which oneelement is integral with another element, i.e. one element isessentially part of the other element. This definition also applies towords of similar meaning, for example, “joined”, “connected”, “coupled”,“mounted”, “bonded”, “fixed” and their derivatives.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. For example, unless specifically stated otherwise,the size, shape, location or orientation of the various components canbe changed as needed and/or desired so long as the changes do notsubstantially affect their intended function. Unless specifically statedotherwise, components that are shown directly connected or contactingeach other can have intermediate structures disposed between them solong as the changes do not substantially affect their intended function.The functions of one element can be performed by two, and vice versaunless specifically stated otherwise. The structures and functions ofone embodiment can be adopted in another embodiment. It is not necessaryfor all advantages to be present in a particular embodiment at the sametime. Every feature which is unique from the prior art, alone or incombination with other features, also should be considered a separatedescription of further inventions by the applicant, including thestructural and/or functional concepts embodied by such feature(s). Thus,the foregoing descriptions of the embodiments according to the presentinvention are provided for illustration only, and not for the purpose oflimiting the invention as defined by the appended claims and theirequivalents.

What is claimed is:
 1. A display device comprising: a display panel; alight source that emits light from a rear side relative to the displaypanel toward the display panel; and a reflective sheet that is disposedon the rear side relative to the display panel, and reflects the lightfrom the light source toward the display panel, the reflective sheetincluding a four-sided bottom face part with two pairs of mutuallyopposing sides, a first peripheral portion extending from one of thesides of the bottom face part, and a second peripheral portion with afirst section extending from adjacent one of the sides of the bottomface part that is adjacent to the one of the sides and a second sectionextending from the first section, the bottom face part and the secondsection of the second peripheral portion partially overlapping with eachother and the first peripheral portion and the second section of thesecond peripheral portion partially overlapping with each other at alocation between ends of the one of the sides of the bottom face part toform one of side face parts of the reflective sheet while the reflectivesheet is installed to the display device, the first section of thesecond peripheral portion forming adjacent one of the side face parts ofthe reflective sheet that is adjacent to the one of the side face partsof the reflective sheet while the reflective sheet is installed to thedisplay device.
 2. The display device according to claim 1, wherein thesecond section is folded relative to the first section to form a cornerportion of the reflective sheet between the one of the side face partsof the reflective sheet and the adjacent one of the side face parts ofthe reflective sheet while the reflective sheet is installed to thedisplay device.
 3. The display device according to claim 1, wherein thefirst peripheral portion and the second section of the second peripheralportion have end edges, respectively, that are adjacent to each otherand extend in directions intersecting with the one of the sides of thebottom face part, respectively, while the reflective sheet is developedin a plane.
 4. The display device according to claim 3, wherein thereflective sheet further includes a third peripheral portion with afirst section extending from opposing one of the sides of the bottomface part that is opposite the adjacent one of the sides of the bottomface part and a second section extending from the first section, thefirst peripheral portion and the second section of the third peripheralportion partially overlapping with each other at a location between theends of the one of the sides of the bottom face part to form the one ofthe side face parts of the reflective sheet while the reflective sheetis installed to the display device.
 5. The display device according toclaim 4, wherein the first peripheral portion and the second section ofthe third peripheral portion have second end edges, respectively, thatare adjacent to each other and extend in directions intersecting withthe one of the sides of the bottom face part, respectively, while thereflective sheet is developed in a plane.
 6. The display deviceaccording to claim 1, wherein the second section of the secondperipheral portion has a side edge that is adjacent to the one of thesides of the bottom face part and extends along the one of the sides ofthe bottom face part.
 7. The display device according to claim 1,further comprising a support member supporting the bottom face part ofthe reflective sheet from the rear side.
 8. The display device accordingto claim 7, wherein the first peripheral portion and the second sectionof the second peripheral portion have flaps that extend from outer edgeportions of the first peripheral portion and the second section of thesecond peripheral portion, respectively, the flaps of the firstperipheral portion and the second section of the second peripheralportion being disposed on an outer peripheral part of the support membersuch that the flaps partially overlap with each other while thereflective sheet is installed to the display device.
 9. The displaydevice according to claim 1, wherein the bottom face part has arectangular shape, with the one of the sides of the bottom face partbeing shorter than the adjacent one of the sides of the bottom facepart.
 10. The display device according to claim 1, wherein the bottomface part has a rectangular shape, with the one of the sides of thebottom face part being longer than the adjacent one of the sides of thebottom face part.
 11. The display device according to claim 1, whereinthe reflective sheet further includes a fourth peripheral portion with afirst section extending from the other opposing one of the sides of thebottom face part that is opposite the one of the sides of the bottomface part and a second section extending from the first section, thefirst section of the second peripheral portion and the second section ofthe fourth peripheral portion partially overlapping with each other at alocation between ends of the adjacent one of the sides of the bottomface part to form the adjacent one of the side face parts of thereflective sheet while the reflective sheet is installed to the displaydevice.
 12. The display device according to claim 4, wherein the bottomface part and the second section of the third peripheral portionpartially overlap with each other while the reflective sheet isinstalled to the display device.
 13. The display device according toclaim 12, wherein the bottom face part and the second section of thefourth peripheral portion partially overlap with each other while thereflective sheet is installed to the display device.